camera: updated e90 camera_definition

This updates from version 18 to version 20 as contained in
E90 v1.0.56.

plugins/camera/camera_definition_files/e90.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8" ?>
 <mavlinkcamera>
-    <definition version="18">
+    <definition version="20">
         <model>E90</model>
         <vendor>Yuneec</vendor>
     </definition>
@@ -949,6 +949,13 @@
         <parameter name="CAM_ZOOM" type="uint32" control="0">
             <description>Camera Zoom</description>
         </parameter>
+        <parameter name="CAM_FILENUMOPT" type="uint8" default="0">
+            <description>File Numbering Option</description>
+            <options>
+                <option name="Auto Reset" value="0" />
+                <option name="Sequential" value="1" />
+            </options>
+        </parameter>
     </parameters>
     <localization>
         <!-- If no appropriate locale is found, the original (above) will be used -->